Project plots every tree on main campus

Last fall nearly 20 Calvin biology students went sleuthing on campus, meter sticks, notebooks and GPS devices in hand. The goal? To document every tree of at least five inches in diameter on the west side of campus—all 3,516 of them.

The tree inventory project was the brainchild of biology professor Dave Warners.

“As we start thinking about a more sustainable campus and trying to become carbon neutral, it seemed to make sense that we needed to document the trees on campus,” Warners said. “In order to know how much carbon sequestration we have on campus, we have to know the number and size of trees.”

So Warners partnered with geography professor Jason Van Horn, a geographic information systems (GIS) specialist, to produce the college’s first tree inventory. The professors were assisted by students in Van Horn’s GIS class and Warners’ plant taxonomy class.

Measuring, researching, mapping

Van Horn’s students developed a data dictionary—a method for data collection that includes an attributes’ table—on the college’s state-of-the-art hand-held GPS receivers. Warners’ students then took those receivers and entered data—including species, diameter, estimated height, estimated canopy, health and habitat—for every one of Calvin’s trees.

“This project was fantastic for my students,” said Van Horn. “This kind of learning is directly applicable to the job industry; expertise in GPS technology is an extremely marketable skill.”

Warners’ students also received valuable training on the GPS units, and they were able to put their tree identification skills to the test.

Among the summary statistics was the total number of trees (3,516), the number of species (112), the number of landscaped vs. natural trees (1138/2378) and the number of each type of tree: Norway Spruce is the most common at 305. There are 194 Red Oak trees and 157 Sugar Maples. The Kentucky Coffee Tree is the most unique, according to Warners; there are three of these on campus.

One student wanted to take the project a step further and make the data more user-friendly. So, under Warners’ direction, junior geography major Owen Selles spent this past summer incorporating the data into an online tree map.

“A lot of people are pretty much oblivious to trees,” said Selles. “As people, we really need to value trees more. They add so much value and beauty to our place.

“I felt like if people knew more about the trees, they would feel more connected to them. That’s what happened to me: I enjoyed a lot of time with trees over the summer.”

The online map includes all of the information gathered by Warners’ class about each tree on campus; trees can be searched by species, by health and by a number of other categories.

The tree inventory/map is especially beneficial to Bob Speelman, a certified arborist and the college’s supervisor of landscape maintenance. “What was helpful was putting numbers with things like the native and non-native species and the diversity we would like to achieve and … setting goals for the amount of canopy cover,” he said.

Identifying threats

The map makes it easier to identify and treat trees like the White Ash, which is susceptible to pests like the Emerald Ash Borer, Warners added: “You can just pull up the map and see all of the White Ash trees on campus; it’s a very powerful tool for taking care of trees.”

The largest and, most likely, the oldest tree on campus is the Red Oak directly in front of the Spoelhof Center. It is well over 200 years old,” said Warners, “and its value is probably $20,000 to $30,000.” Warners would like to add to the inventory the category of the trees’ value, as calculated by each tree’s ability to clean the air, curb stormwater runoff, raise property value, sequester carbon and reduce energy costs.

Calculating the dollar value recognizes the trees’ worth, but also allows one to make a more informed decision when it comes to building projects on campus, he said: “And you can talk knowledgeably about mitigation, about planting trees of comparable value elsewhere.”

Personalizing the map

In the future, Selles would like to see the map become interactive so that people could add memories of particular trees on campus or information about the history of an individual tree or specifics about one of the 25 memorial trees: trees planted in honor of individuals who have died.

As a student at Calvin in the early 1980s, Speelman specifically remembers the beautiful sugar maple outside his window near Schultze Residence Hall, “In the fall, with all of the reds and yellows, it lit up the whole side of the building. I’m sure I loved trees before that even, but that one has meaning to me.”

Memories like Speelmans’ and histories of why trees were planted would connect people to trees, Selles said.

“We’re called to be stewards and the first step of being serious stewards is knowing what it is you’re stewarding,” said Selles. “That’s what makes this map worthwhile.”